The present invention relates to a dust filter bag for a vacuum cleaner, having a holding plate which has a tightly closed opening for a pipe connection of the suction part of a vacuum cleaner, the opening being adapted to be closed from the outside by a separate closure flap which has an insertion region.
Such dust filter bags are already known in various developments. Reference is had in this connection to German Utility Model 78 32 780 and to German Utility Model 90 01 528.
Such dust filter bags usually have a stiffened upper holding plate, for instance of a thicker cardboard material, while the dust filter bag itself usually consists of a cloth-like cellulose material. By means of the holding plate the dust filter bag can be inserted into the apparatus and connected to the aforementioned pipe connection. The opening of the dust filter bag is usually closed by a packing which consists of a circular rubber part resting from the bottom against the opening. This rubber part rests from the inside against the opening with a certain initial tension. When the dust filter bag is inserted into the vacuum cleaner, the packing is forcefully opened by the pipe connection. Upon the removal of the dust filter bag, the packing is to apply itself again against the opening from the inside. Actually, however, this does not take place with the desired reliability, particularly when the dust filter bag is full. When a completely full dust filter bag is removed from the vacuum cleaner, its handling can cause the dust to reemerge very quickly from the inside of the dust filter bag in the form of clouds of dust, which is very unpleasant. In order to remedy this, it has already been proposed in the above-mentioned prior art to provide a separate closure flap by means of which the opening can be closed from the outside upon removal of the dust filter bag. The known closure flap, however, is not satisfactory in every respect. On the one hand, it is occasionally perceived as troublesome upon handling a new dust filter bag, particularly when inserting the bag, while, on the other hand, the closing action of this closure flap is also not yet considered sufficient in all cases.